Aqueous resin solution catalyzed with two salts and process of impregnating fibers therewith



AQUEOUS RESINISO'LUTION CATALYZED WITH TWO SALTS AND PROCESS OFIMPREGNATING FIBERS THEREWITH Oct. 31, 1961 J J RYAN EI'AL 3,006,879

Filed Aug. 12, 1958 6 Sheets-Sheet 1 Inventors e J' HN II'MES RYA-N 4-PETER To/w TAYLOR Attorney:

Logurithm to base IQ of molar concentration 1951 J. J. RYAN EI'AL 3,00,879

AQUEOUS RESIN SOLUTION CATALYZED WITH TWO SALTS AND PROCESS OFIMPREGNATING FIBERS THEREWITH Filed Aug. 12, 1958 6 Sheets-Sheet 2Logori thm to base IO of molar concentration Tc-HN TA M6 5 1%??? 4 PETERJOHN TAYlolZ A ttorney Oct. 31, 1961 J. J. RYAN ETAL 3,006,879

AQUEOUS RESIN SOLUTION CATALYZED WITH TWO SALTS AND PROCESS OFIMPREGNATING FIBERS THEREWITH Filed Aug. 12, 1958 6 Sheets-Sheet 5Logorithm to base IQ of molar concentration Ln o v- "3 N- Inventor: HNTAIHFS R AN PETER Town TAYLOR Attorneys J. J. RYAN ETAL 3,006,879AQUEOUS RESIN SOLUTION CATALYZED WITH TWO SALTS AND PROCESS OFIMPREGNATING FIBERS THEREWITH Oct. 31, 1961 Filed Aug. 12, 1958 6Sheets-Sheet 4 Logorithm to base IO of molar concentration Logorithm tobase IQ of molar concentration v m 11 lo Inventor THIN IMES RYAN PETERToHN TAYLOR w WW Attorneys 06L 1961 J. J. RYAN El'AL 3,006,879

AQUEOUS RESIN SOLUTION CATALYZED WITH TWO SALTS AND PROCESS OFIMPREGNATING FIBERS THEREWITH j'of/N FAME: KYAN PETER 'I H/v TAYLOR 1 Byr QM $1 M W Attorneys Oct. 31, 1961 J. J. RYAN EI'AL AQUEOUS RESINSOLUTION CATALYZED WITH TWO SALTS AND PROCESS OF IMPREGNATING FIBERSTHEREWITH 6 Sheets-Sheet 6 Filed Aug. 12, 1958 5:9:588 6 E 3 o 33 2 EQ lLL United States Patent Filed Aug. 12, 1958, Ser. Claims priority,application Great Britain Aug. 14, 1957 13 Claims. (Cl. 260-29.3)

This invention relates to improvements in the formation of aldehydecondensation products and in the catalysis thereof, and is acontinuation-in-part of co-pending application Serial No. 581,508, filedApril 30, 1956.

The condensation of many compounds, especially amino compounds, withaldehydes can be catalysed by acids. It is not, however, convenient inmany cases to add free acid to solutions containing the ingredients ofaldehyde condensation products. For example, mixtures of the ingredientsof amino-aldehyde condensation products and free acid are unstable andcan undergo premature condensation. (The term ingredients when usedherein includes partial condensates, i.e. the so-called intermediatecondensation products.) Such acid catalysts generally have to be addedat the last moment before the acid-catalysed condensation is required totake place and such condensation is customarily effected by heating. Itis, therefore, more convenient to have a solution of the ingredients ofan aldehyde condensation product, especially an amino-aldehydecondensation product, containing a substance which does not catalyse thecondensation to any substantial extent at ordinary temperatures, butdoes catalyse it when the solution is heated.

Accordingly, in the formation of condensation products from aminocompounds and formaldehyde, e.g. urea and formaldehyde or melamine andformaldehyde, it is customary to add to an aqueous solution of theresin-forming ingredients, an ammonium salt of a strong acid such asammonium chloride or an ammonium phosphate. Such a solution has a fairlyhigh pH at ordinary temperatures so that the condensation does notproceed at all or proceeds only slowly, but on heating the pH falls, dueto a chemical reaction between the ammonium ion of the ammonium salt ofthe strong acid and the formaldehyde or the intermediate condensationproduct causing the strong acid to be liberated, so that thecondensation is catalysed and proceeds more rapidly. However, there arecertain disadvantages, which will be referred to later, attending theuse of ammonium salts because of the chemical reaction referred toabove.

One object of the invention is to overcome these disadvantages. Anotherobject is to provide a solution containing the ingredients of analdehyde condensation product in which the acidity required for thefurther condensation of said ingredients can be developed withoutchemical reaction between any of said ingredients and any addedsubstance. Another object is to provide a solution containing theingredients of an amino-aldehyde condensation product in which theacidity required for further condensation of said ingredients can bedeveloped Without the presence in said solution of any ammonium salt.Another object is to provide a solution containing the ingredients of analdehyde condensation product in which the acidity required for furthercondensation of said ingredients can be developed by mere removal ofsolvent therefrom. A further object is to provide a solution containingthe ingredients of an aldehyde condensation product which, onevaporation, will undergo a sudden and substantial increase in aciditywhen almost all the solvent has been removed. A still further object isto provide an "ice aqueous solution, particularly useful for treatingtextile materials, of a crystalloidal intermediate condensation productof urea and formaldehyde or melamine and formaldehyde which is stable atroom temperatures, but will develop sufiicient acidity to catalyse theformation of resin from said condensation product on evaporation and/orheating, especially such a solution containing little or no ammoniumsalt. Another object of the invention is to provide a solution ofpotential acid catalysts which can be diluted when required for use.These and other advantages can be secured by making use of a littleknown property of certain acid salts, of which magnesium dihydrogenphosphate is a convenient example. The term phosphoric acid is usedherein to mean orthophosphoric acid, and the term phosphate to meanorthophosphate.

When an aqueous solution of sodium dihydrogen phosphate is concentratedby evaporation at room temperature, the salt which first separates outis sodium dihydrogen phosphate. By the term room temperature when usedherein, we mean substantially 20 C. On the other hand, when an aqueoussolution of magnesium dihydrogen phosphate is concentrated byevaporation at room temperature, the salt which first separates out ismagnesium monohydrogen phosphate. During the removal of solvent byevaporation, the pH of both these solutions falls; but in the case ofthe solution of magnesium dihydrogen phosphate, the effect of theseparation of magnesium monohydrogen phosphate is that the rate ofincrease of acidity with increase in the proportion of magnesium insolution becomes greater after the point is reached at which theseparation begins.

Moreover, when an aqueous solution of magnesium dihydrogen phosphate ismerely heated, magnesium monohydrogen phosphate may separate from thesolution at about 70 C., this separation being accompanied by a suddenincrease in acidity. This appears to be due to the fact that at thattemperature a hydrate of magnesium monohydrogen phosphate is formedwhich is less soluble at that temperature than either magnesiumdihydrogen phosphate or the form of magnesium monohydrogen phosphatestable below that temperature. Such hydrate will, accordingly, separateon heating the solution to the above transition temperature even withoutevaporation of the solution, provided that the initial concentration ofthe magnesium dihydrogen phosphate is sufliciently high. Atconcentrations above 10 grams per litre, such separation will take placefrom simple aqueous solution on mere heating to the above transitiontemperature.

The first effect can be brought about in any ionising solvent for themetal dihydrogen phosphate from which a less acid salt first separatesout on evaporation. Thus, an ethanol solution of sodium dihydrogenphosphate exhibits the first effect. The second efiect can also bebrought about in any ionising solvent capable of forming with magnesiummonohydrogen phosphate a complex or crystal form which will separatefrom the solution on mere heating, as does the hydrate when water isused as the ionising solvent.

We have found that these efiects, or at least the first one, can also berealised with acid salts of polybasic acids, other than magnesiumdihydrogen phosphate. Solutions of acid salts from which a less acidsalt will separate before such acid salt on removal of solvent and/or onheating can be obtained from polybasic acids other than phosphoric acid,for example phosphorous acid, pyrophosphoric acid, malonic acid, malicacid, maleic acid, tartaric acid and succinic aid.

Examples of acid salts whose solutions can be used are:

Calcium dihydrogen phosphate Strontium dihydrogen phosphate Nickeldihydrogen phosphate Lithium dihydrogen phosphate Lithium monohydrogenphosphate Calcium hydrogen phosphite Magnesium dihydrogen pyrophosphateCalcium hydrogen malonate Strontium hydrogen malonate Calcium hydrogenmalate Calcium hydrogen maleate Barium hydrogen maleate Strontiumhydrogen tartrate Calcium hydrogen succinate It is simply necessary thatthe acid salt be that of a metal of which a less acid salt with the samepolybasic acid is precipiated before said acid salt on mere removal ofsolvent from and/or on heating of the solution. Such metal willhereinafter be referred to as a selected metal.

By the term acid salt is meant a salt in which less than all of thereplaceable hydrogen atoms in the polybasic acid molecule are replacedby the selected metal, and the other replaceable hydrogen atom or atomsis or are unreplaced.

By the term less acid salt is meant a salt in which more of thereplaceable hydrogen atoms in the polybasic acid molecule are replacedby the selected metal than in the case of said acid salt; the termincludes salts in which all of the replaceable hydrogen atoms are soreplaced.

These efiects are reversible. This means that if such solutions, afterbeing concentrated by evaporation (or heated) are again diluted (orcooled as the case may be), the separated salt is re-dissolved and thepH rises again. These effects can be readily demonstrated by thefollowing experiments with magnesium dihydrogen phosphate.

(A) Precipitation and development of acidity by evaporation withoutheating.A quantity of pure crystalline magnesium dihydrogen phosphatedihydrate, Mg(H PO4) .2H O, was disolved in an equal weight of water.After three days standing in the air so that evaporation took place atroom temperature, it was found that crystals had deposited. These werefiltered oif and identified spectroscopically as magnesium monohydrogenphosphate.

A- sample of the original solution was diluted ten times with'water andwas found to have a pH of 3.6. A sample of the filtrate taken afterprecipitation had occurred and similarly diluted ten times with waterwas found to have a pH of 3.0.

(B) Precipitation and development of acidity by heating withoutevaporation.-A 10% solution of pure crystalline magnesium dihydrogenphosphate dihydrate was made and was found to be stable indefinitely atroom temperatures; its pH was 3.6. This solution was then warmed at therate of 10 C. per hour and at 69 C. a slight powdery precipitate 'beganto separate. On refluxing for minutes this solution deposited a furtherquantity of crystals which were filtered off and identifiedspectroscopically-as magnesium monohydrogen phosphate. The pH of thefiltrate was 2.8.

(C) Precipitation and development of acidity by evaporation and reversalof the efiect.An N/IO solution of magnesium dihydrogen phosphate wastaken and found to be alkaline to bromophenol blue. A quantity of thiswas evaporated to dryness and water was then added to restore the volumeto its original level. The solid did not all re-dissolve but the mixturewas now strongly acid to bromophehol blue. On shaking, the mixturebecame more alkaline, and the solid gradually re-dissolved when themixture was allowed to stand at room temperature over the course of afew days, the mixture returning to its original colour.

(D) Precipitation and develpment of acidity by removal of solventwithout evaporalion.To an N/10 solution of magnesium dihydrogenphosphate, ethyl alcohol was added. There was instant precipitation of asolid and the solution because acid to bromophenol blue.

In the present invention, advantage is taken of either or both of theseeffects, i.e. development of acidity by removal of solvent and byheating, to bring about the acid catalysis of the condensation of aminocompounds with aldehyde.

We have found that these elfects can be brought about in solutionscontaining the ingredients of aldehyde condensation products. It thusbecomes possible to make solutions, in ionising solvents such as wateror methanol, containing the ingredients of such condensation products,which solutions have a suificiently high pH to enable them to be keptfor long periods'without any substantial condensation taking place butwhich, on removal of solvent and/or on heating, will show a rapid fallin pH after a critical concentration and/or temperature has beenreached, thereby enabling the acidcatalysed condensation to take place.In order that such condensation be effectively acid-catalysed, it isnecessary that the polybasic acid be one having a first dissociationconstant in water of not less than 10*.

The critical concentration referred to above is the concentration atwhich the solution becomes saturated with respect to the less acid saltwhich separates out before the acid salt. The critical concentrationdepends upon the nature of the selected metal, upon the nature of thepolybasic acid and upon the ionising solvent employed and may be alteredby other ingredients in the solution, especially any common ions.However, it is generally possible to determine the criticalconcentration for any solution by making pH measurements at variousconcentrations and at the temperature at which it is desired to use thesystem and drawing a graph showing the relationship between pH andconcentration. The slope of the curve alters suddenly at the point wherethe less acid salt of the selected metal begins to separate out. Severalsuch graphs are described hereinafter. The word concentration refers tothe concentration of the selected metal in solution.

The critical temperature, when it exists, is a transition temperaturebetween two phases and is therefore independent of the other ingredientsof the solution.

If supersaturation occurs, separation of the less acid salt of theselected metal may not take place immediately the critical concentrationand/or temperature is reached. This, however, is no disadvantage formost purposes. The separation of the less acid salt will merely bedelayed and when it does take place there will be a sudden fall in pH.

According to the present invention there is provided a solution in anionising solvent of the ingredients of an aldehyde condensation productwhose formation is catalysed by acid, containing in solution an acidsalt of a polybasic acid having a first dissociation constant in Waterof not less than l0 with a metalof which a less acid salt with the samepolybasic acid is precipitated before said acid salt on removal ofsolvent from and/or on heating of the solution. Preferably the solutioncontains a dihydrogen phosphate of a metal whose tn'metal phosphate ormonohydrogen phosphate will separate before its dihydrogen phosphate onremoval of solvent and/or on heating of the solution.

It is clear that if a solution is made of such an acid salt of apolybasic acid, the concentration of which exceeds the criticalconcentration, an immediate precipitation of the less acid salt willresult. There is, therefore, an upper limit to the concentration whichcan be achieved in a stable solution of the said acid salt.

-It is, however, convenient for many purposes to have solutions of highconcentration which can be diluted when they are required for use. It isan object of the present invention to increase the criticalconcentration thus enabling solutions of the said acid salts to be obtained of higher concentration than have hitherto been possible.

According to the present invention, this object is achieved by providinga solution in an ionising solvent of an acid salt of a polybasic acidhaving a first dissociation constant in water of not less than l with aselected metal of which a less acid salt with the same polybasic acid isprecipitated before said acid salt on removal of solvent from thesolution, the critical concentration (as hereinbefore defined) of whichsolution is increased by the presence of free acid dissolved therein inan amount insufiicient to prevent precipitation of the less acid salt onremoval of solvent from the solution.

A very convenient way of producing such a solution containing thedihydrogen phosphate of such a metal is to introduce into the solutionof the ingredients of the amino-aldehyde condensation product thedihydrogen phosphate of a base whose dihydrogen phosphate will separatefrom solution on removal of solvent and/ or on heating before itsmonohydrogen phosphate, such as an alkali metal or ammonium dihydrogenphosphate, and also a salt of the selected metal, such as magnesium,with an acid which is stronger than phosphoric acid. it is, of course,desirable that neither the salt of the selected metal with such acidstronger than phosphoric acid, nor the dihydrogen phosphate of the baseshould separate first from the solution on removal of solvent and/ or onheating, at the temperature to which the solution is subjected. Asolution containing an acid salt of a selected metal with a polybasicacid, other than phosphoric acid, having a first dissociation constantin water of not less than can be produced in analogous manner.

Accordingly, the invention includes a solution in an ionising solvent ofthe ingredients of an aldehyde resin whose formation is catalysed byacid containing in solution an acid salt, especially an alkali metal orammonium acid salt, of a polybasic acid having a first dissociationconstant in water of not less than 10- (such as the dihydrogenphosphate) and also a salt with an acid stronger than said polybasicacid of a metal of which a less acid salt with said polybasic acid (suchas its trimetal phosphate or monohydrogen phosphate) will separatebefore the acid salt of said metal from the solution on removal ofsolvent therefrom and/or on heating thereof.

Such solution can be made in high concentration by adding free acidthereto in an amount which is insufficient to prevent precipitation ofthe less acid salt.

According to the present invention, the critical concentration of thesolution is increased by the presence of free acid dissolved therein.The amount of salts held in solution can therefore be raised so that thetotal amount of acid produced is also increased. By using the solutionsof the present invention, therefore, the critical concentration can heraised to a point where the total amount of acid formed is such that anytraces of alkali present will no longer have a substantial effect on thefinal pH achieved.

Preferably the free acid is the same polybasic acid as that which formsthe anion of the acid salt in the solution. When acids other than thesame polybasic acid are used, it is essential that such other acidneither precipitates any component of the system, nor forms any saltwith the selected metal which will separate from the solution before theless acid salt on removal of solvent,

The acid salt may be, for example, a sodium or potassium salt ofphosphoric acid. The selected metal for use with salts of phosphoricacid may be, for example, lithium, barium, calcium, strontium,magnesium, zinc, copper, iron (ferrous), manganese, cadmium or cobalt.Ferrous salts are not suitable for use with salts of phosphoric acid ita pH below about 3.5 is required.

The acid stronger than the said polybasic acid may be, for example,hydrochloric acid or sulphuric acid or nitric acid provided that theresulting solution does not unduly attack the ingredients of thealdehyde resin or the material which is to be treated with the solution.

It is preferred to use acid salts of a metal such as an alkali metal,most suitably acid salts of sodium; the acid salts of ammonium arepreferably not used since they can give rise to some reaction with thealdehyde or intermediate condensation product in the solution.

A solution as defined above comprises a system of salts which behaves,as regards pH change beyond the critical concentration and/ or beyondthe critical temperature, as if it were simply a solution of the acidsalt of the selected metal. However, the system must be such that the pHat the critical concentration is sufficiently high, or can be madesufiiciently high by buffering as hereinafter explained, to preventpremature condensation of the aldehyde resin-forming ingredients.

A few systems which have been found useful are:

(a) Sodium dihydrogen phosphate and magnesium chloride.

(b) Sodium dihydrogen phosphate and magnesium sulphate.

(0) Sodium dihydrogen phosphate and calcium chloride.

(d) Sodium hydrogen malonate and strontium chloride.

(e) Sodium hydrogen maleate and barium chloride.

(1) Sodium dihydrogen phosphate and lithium chloride.

(g) Sodium dihydrogen phosphate and nickel sulphate.

(h) Sodium dihydrogen phosphate and strontium chloride.

(i) Disodium hydrogen phosphate and lithium chloride.

(j) Potassium hydrogen phosphate and calcium chloride.

(k) Disodium dihydrogen pyrophosphate and magnesium sulphate.

(1) Sodium hydrogen maleate and calcium chloride.

(m) Sodium hydrogen malonate and calcium chloride.

(n) Sodium hydrogen succinate and calcium chloride.

(0) Sodium hydrogen tartrate and strontium chloride.

(p) Sodium hydrogen malate and calcium chloride.

The acid salt of said polybasic acid and the salt of a selected metalwith an acid stronger than said polybasic acid are preferably used insubstantially equivalent proportions, although an excess of one or theother up to about 3 to l equivalents does not give rise to anyinconvenience. It is desirable, however, to employ such relativeproportions that neither salt will separate from solution before thedesired separation of less acid salt takes place, since the salt whichso separates serves no useful purpose.

At concentrations below the critical concentration and/or attemperatures below the critical temperature, the solutions containingthe ingredients of an aminoaldehyde condensation product are quitestable due to their pH value. By stable we mean that the ingredients ofthe amino-aldehyde resin in the solution will not readily condense towater-insoluble condensation products on standing. Solutions containingthe ingredients of ureaformaldehyde resin having a urea to formaldehyderatio of 121.6 and a solids content of 20% weight/volume are stable at20 C. for a period of not less than about one hour when the pH remainsat 4, of not less than about 8 hours when the pH remains at 5 and of notless than about 24 hours when the pH remains at 5.5. It is thereforedesirable that the pH value of the solutions should initially be notless than 5 One reason why it is preferable to use an acid salt of ametal such as an alkali metal rather than an acid salt of ammonium, whena salt of an acid stronger than said polybasic acid is also employed, isthat the pH of solutions containing salts of metals such as alkalimetals remains unchanged on mere standing, whereas the pH of solutionscontaining ammonium salts falls on mere standing because of the reactionalready referred to with the aldehyde or intermediate condensationproduct which can proceed slowly even without heating; no such reactiontakes place when a metal such as an alkali metal salt is employed. It isalso desirable to use acid metal salts which are not substantiallyhydrolysed in solution.

Such solutions containing an acid salt of a polybasic acid and a salt ofthe selected metal with an acid stronger than the polybasic acid havehitherto been more convenient to use than those containing the preformedacid salt of the selected metal, since in preparing the former, highlyconcentrated solutions of the individual ingredients can be used whichare highly advantageous for storage purposes. Nevertheless, solutionsobtained by formation of the acid salt of the metal in the solution arenot always the most advantageous for all purposes. The formation in thesolution of the acid salt of the selected metal of'necessity introducesinto the solution ions other than those of the selected metal, and thepolybasic acid which other ions, on sufiicient concentration of thesolution, combine to form undesirable precipitates.

Thus, for example, when the catalyst to be used is magnesium dihydrogenphosphate, and it is formed in solution by the use of sodium dihydrogenphosphate and magnesium sulphate, sodium sulphate is formed as anundesirable precipitate on sufiiciently concentrating the solution.'Such undesirable precipitates are not, of course, formed when thesolution contains a preformed acid salt of the selected metal, but suchsolutions have not hitherto been convenient in practice because of theupper limit on the possible concentration of the acid salt of theselected metal.

It is a particular feature of the persent invention that suchundesirable precipitates can be avoided whilst retaining the practicaladvantages inherent in the use of concentrated solutions of thecatalyst. This feature is particularly relevant where the solutions areused as catalysts in hardening urea-formaldehyde resins in the treatmentof textile materials.

The ratio of the selected metal ion to that of the more acid anion ofthe polybasic acid which will produce the greatest hydrogen ionconcentration on concentrating an aqueous solution of the more acid saltof a polybasic acid to a predetermined solids content, may not be thationic ratio which is present in the acid salt itself. For example, in asystem where the selected metal is magnesium and the more acid anion ofthe polybasic acid is the dihydrogen phosphate anion, calculation orsimple experiment will show that the optimum molar ratio of magnesiumcation to dihydrogen phosphate anion from the point of view ofproduction of hydrogen ion concentraiton is 1:1. However, the ratio ofmagnesium cation to dihydrogen phosphate anion in magnesium dihydrogenphosphate is 1:2.

In such cases it is advantageous to adjust the ionic ratio occurring inthe solution of the preformed acid salt to conform as closely aspossible to the optimum ratio by adding, in the form of a salt of theselected metal with an acid stronger than the polybasic acid, or in theform of a metal salt of the polybasic acid having a greater solubilitythan either the acid salt or less acid salt of the selected metal withthe polybasic acid, more of the ion in which the solution is deficient,or by adding as much as it is possible to do so without forming asupersaturated solution of the solids.

As an example of the above modification, it has been found that if thephosphate concentration of an aqueous solution of magnesium dihydrogenphosphate is decreased by 30%, and the magnesium concentration isincreased by 40%, by the appropriate dilution of the solution andaddition of magnesium sulphate, the resulting solution possessesapproximately the same critical concentration as before with respect tothe selected metal, i.e. magnesium. It is also more eflicient for agiven initial concentration of dihydrogen phosphate anion than theoriginalsolution of magnesium dihydrogen phosphate when it isused as apotential acid catalyst for forming .resin from an intermediatecondensation product of urea and formaldehyde. Above the criticalconcentration, however, at any given pH, the solution containing theincreased quantity of magnesium has a lower concentration of dihydrogenphosphate anion than a solution with less magnesium which will form theresin equally efliciently. Further, by this modification there is asaving in cost, since magnesium sulphate is less expensive thanorthophosphoric acid from which the dihydrogen phosphate is formed insolution. A further advantage of this modification is that noundesirable by-products such as sodium sulphate are formed.

The optimum mole ratio of selected metal ion to the more acid salt anionof the polybasic acid will depend on the basicity of the polybasic acid,the valency of the selected metal, and on the number of hydrogen atomsin the anion of the less acid salt of the polybasic acid. When theselected metal is divalent, the optimum ratios for triand di-basic acidsare as follows;

1 SM=selected metal. 2 MASA=more acid salt anion.

When the selected metal is lithium and the polybasic acid is phosphoricacid, the optimum mole ratio of lithium to dihydrogen phosphate anion is3:1.

If the initial pH of the solution is too low for it to have whateverstability may be desired, the pH can be raised by buffering. Suchbuffering is brought about by the addition to the solution of asubstance which will increase the concentration of anions of the lessacid salt (eg monohydrogen phosphate ions) therein, either directly orindirectly. Such direct increase can be brought about by the addition ofa soluble salt providing such anions (e.g. a soluble metal m onohydrogenphosphate such as an alkali metal monohydrogen phosphate). Indirectincrease can be brought about by the addition of a substance which willreduce the hydrogen ion concentration. Examples of such substances areammonia or organic bases, alkali metal hydroxides and alkali metal saltsof acids weaker than said polybasic acid, such as boric acid. Where thepolybasic acid is phosphoric acid and the less acid salt of a selectedmetal which separates is a monohydrogen phosphate, trialkali metalphosphates can be used as buffers. There is a limit to the extent towhich the initial pH of the solution can be raised 'by buflering, thislimit being determined, for a given concentration of polybasic anion, bythe amount of free selected metal ions in solution. The lower theconcentration of free selected metal ions, the greater is the amount bywhich the solution can be bufiered. When buffering is eifected with asalt of an acid weaker than said polybasicv acid, the number ofequivalents added must not exceed the number of equivalents of hydrogenion which carrbe liberated by precipitation of the less acid salt. Thiswill be further explained hereinafter with the aid of the graphs alreadyreferred to.

When the solutions contain the ingredients of an aminoaldehydecondensation product, the extent to which the solvent must be removedfrom the solution by evaporation to initiate the separation of the lessacid salt of a selected metal will influence the nature of theaminoaldehyde condensation products which are formed. If, on evaporationof such an aqueous solution of the present invention, separation takesplace at such a stage that the pH falls low enough to give rise towater-insoluble condensation products at a time when there is still asubstantial proportion of water present, the condensation product willbe precipitated in particulate form. If, on the contrary, it is possibleby evaporation to remove substantially all of the water before the pHfalls low enough to give -rise-to waterinsoluble condensation products,then the resulting products will be resinous in character. Even if spineof the condensation product is precipitated from solution in particulateform, there will generally also be an appreciable amount produced inresinous form on fur ther concentration.

The solutions of the present invention may be used for the treatment offibrous materials such as fibres, yarns, fabrics or paper to producealdehyde condensation products therein and/or thereon. They may also beused for other purposes for which solutions of thermo-hardening aldehyderesins arecommonly employed, for example as adhesives or bonding agentsor for the preparation of thermo-hardened resin objects or for thepreparation of moulding powders. Thus, they may be used for the bondingof glass fibres, for example to form hard bonded glass mats or softbonded glass blocks. They mayalso be used for the bonding of fibres ofglass, cotton or the like in thin sheets, for example for themanufacture of the so-called glass fibre tissue. In particular they areuseful for making bonded non-woven viscose rayon fabrics. They may alsobe used for the production of laminated sheets of paper, wood, leatheror the like. They can be used for the impregnation of pulverulentmaterial such as wood flour and the impregnated material can thereafterbe moulded by heat and pressure. It is possible to dry wood flour whichhas been impregnated with the solution sulficiently to enable it to beground and used like the conventional moulding powders. When so driedand ground the material seems to retain sufiicient solvent to keep theless acid salt in solution. The acidity necessary for furthercondensation to a thermo-hardened product is developed when theresulting moulding powder is moulded under heat and pressure.

It is known that if an amino-aldehyde condensation product inparticulate form is produced in contact with fibres, yarns or fabrics,the particles are deposited thereon and adhere thereto producing aneffect known as delustring. It is also known that if a condensationproduct of resinous character is produced within the fibres then usefuleffects are produced in textile fabrics so treated or textile fabricsmade from the yarns or fibres so treated, these effects being in generalimproved dimensional stability, improved fastness of many dyestuffs andimproved resistance to creasing. It is possible to produce these lattereffects in combination with delustring. It is also known that to produceeffects which have good wash-fastness, a final heating at a low pH isnecessary.

It will be seen, therefore, that the solutions of the pres- .entinvention, in so far as they contain the ingredients of anamino-aldehyde condensation product, are particularly suitable for thetreatment of textile fibres, yarns or fabrics. For this purpose, thefibres, yarns or fabrics are impregnated with the solutions of theinvention and are then dried and heated. During the drying the solutionsare being concentrated by evaporation and a stage is reached at whichseparation of a less acid salt of a selected metal takes place resultingin an increase in the rate at which the pH falls. If the pH falls to asufliciently low value to give rise to the precipitation of condensationproduct from the solutions while they are still in the intersticesbetween the fibres of the textile material, then the condensationproduct will be deposited in particulate form on the fibres producingdelustring. On further drying, the solution remaining in the fibresthemselves will be further concentrated by evaporation with furtherlowering of the pH enabling a final heating to be effected at asufiiciently low pH to form resinous condensation product of goodfastness to washing. Such resinous condensation product, being formedwithin the fibres, gives the known useful efiects hereinbefore referredto. The formation of the resinous condensation product also increasesthe fastness to washing of any delustre effect which may have beenproduced.

Accordingly, ducing a finish on a textile the invention includes aprocess of promaterial which comprises impregnating the textile materialwith a solution, especially invention containing hyde condensation anaqueous solution, of the present the ingredients of an amino-aldehydecondensation product and thereafter subjecting the impregnated materialto drying and heating whereby to eifect'condensation of theresin-forming ingredients upon or within or upon and Within the fibresof the textile material. Thus the impregnated material may be firstdried at a temperature below 100 C. and may thereafter be baked at atemperature above 100 C.

It is preferred to employ, as the ingredients of an aminoaldehydecondensation product, a crystalloidal precondensation product of ureaand formaldehyde or melamine and formaldehyde.

When textile yarns or fabrics of cellulosic material are impregnatedwith aqueous liquors, the fibres themselves will absorb about 25% to 40%of their weight of liquor, depending upon the nature of the fibres.Fibres of viscose rayon or mercerized cotton will absorb about 40%although fibres of unmercerised cotton or linen will absorb only about25% to 30%. Aqueous liquor taken up by the yarns or fabrics in excess ofthat absorbed by the fibres will remain in the interstices between thefibres and is referred to herein as interstitial liquor. It iscustomary, in the treatment of cellulosic yarns or fabrics with aqueousliquors during textile finishing operations, to express the excess ofliquor so that the yarns or fabrics retain a known predeterminedquantity of liquor, generally or of their dry weight. It follows,therefore, that when yarns or fabrics of cellulosic materials are madeto retain about 80%-l00% of their weight of aqueous liquor, from aboutone third to about onehalf of this will be interstitial liquor. It isthis interstitial liquor which first disappears on drying. Accordingly,if the retained liquor can be concentrated by evaporation to such anextent that more than about 50% to 75% of the water is removed beforeany substantial amount of condensation product is precipitated, thenlittle or no delustring will take place. If, however, less than thisamount of the water must be removed before condensation takes place,then delustring will be brought about. Accordingly, in order to producea delustred effect, the aqueous solution should be so composed that whenthe impregnated material is dried, the critical concentration (ashereinbefore defined) is exceeded before the weight of solution retainedin and on the fibres of the textile material falls below 40% (andpreferably before it falls below 60%) by weight based on the weight ofdry unimpregnated textile material.

The ingredients of amino-aldehyde condensation products used in thesolutions of the present invention may have as their amino componenturea or melamine, for example, and as their aldehyde componentformaldehyde or paraformaldehyde, for example. As already stated, theterm ingredients includes partial condensates and one may therefore usein the solutions the water-soluble methylol compounds obtained by thecondensation of urea or melamine with formaldehyde under alkalineconditions.

The methylol ethers derived from urea and formaldehyde or melamine andformaldehyde may also be used; thus the dimethyl ether of dimethylolurea may be used. Such methylol ethers do not, however, give particulateprecipitates suitable for delustring.

According to a modification of the process of producing a finish on atextile material, the solution is formed on and in the textile material,by efiecting the impregnation in two stages. The first stage maycomprise impregnating the textile material with a solution containing anacid salt, especially an alkali metal or ammonium acid salt, of saidpolybasic acid (such as the dihydrogen phosphate), the second stage thencomprising impregnating the textile material with a solution containingthe salt of a selected metal with an acid stronger than said polybasicacid, the textile material being dried between the stages. Eithersolution may contain the ingredients of the amino-aldeproduct.Alternatively the solution used for the first stage may contain the saltof a selected metal with an acid stronger than said polybasic acid, andthe solution used in the second stage, the acid salt, especially analkali metal or ammonium acid salt, of said polybasic acid (such as thedihydrogen phosphate). As before, either solution may contain theingredients of the amino-aldehyde condensation product. In any of thesealternatives, the composition of the solution used in the second stagemust be so chosen that the desired precipitation of less acid salt doesnot take place upon impregnation but requires removal of solvent fromand/ or heating of the solution with which the fabric is so impregnated.

It is preferred to employ solutions which do not contain ammonium ionsor ions of organic bases. Accordingly, if the solution is made with ametal salt of an acid stronger than said polybasic acid, it is (asalready stated) preferred that the acid salt (such as the dihydrogenphosphate) employed be an alkali metal acid salt, especially an acidsalt of sodium. Moreover, if the solution is buttered, it is preferredthat ammonia or organic bases should not be used for this purpose. It isgenerally most convenient to employ the ingredients of theamino-aldehyde condensation product in the form of a water-solublecrystalloidal intermediate condensation product produced in known mannerunder neutral or alkaline conditions. It is preferred to employ such anintermediate condensation product for the preparation of the solutionsof the present invention, but it is preferred also to use one whoseformation has not been catalysed by means of ammonia.

The solutions of the present invention containing the ingredients ofamino-aldehyde condensation products possess a number of advantages overthe solutions containing such ingredients hitherto employed whichsolutions depend for the development of acidity upon decomposition of anammonium salt. Since removal of solvent is required to reduce the pH(except in a case such as that of magnesium dihydrogen phosphate whereseparation of a less acid salt will take place merely on heating to atransition temperature), such solutions of the present invention arequite stable even at temperatures above room temperature. Even in thecase of magnesium dihydrogen phosphate, acidity does not develop below70 C., if the solution is not evaporated. The development of acidity byreaction of ammonium salts with aldehyde or intermediate condensationproducts gives rise to the production of volatile bases which are liableto have an unpleasant odour. Such volatile bases are not produced fromthose solutions of the present invention which do not contain ammonia oran ammonium salt. The use of ammonia and/ or ammonium salts in thesolutions causes the production of hexamine which adversely aflFectslight-fastness of certain direct dyestuifs. Hexamine is not producedwith those solutions of the present invention which do not containammonia or an ammonium salt. Solutions in which the development ofacidity is caused by the reaction of ammonium salts are dependent fortheir eifect upon the free formaldehyde content of the solutions. Thedevelopment of acidity in the solutions of the present invention whichdo not contain ammonium salt is independent of the free formaldehydecontent of the solutions. Even those solutions of the present inventionwhich do contain ammonium salt undergo a development of acidity onremoval of solvent and/or on heating which is independent of any acidityproduced by the reaction of the ammonium salt with free formaldehyde inthe solution. The reaction of the ammonium salt in the known baths is anirreversible decomposition. As already stated the separation of lessacid salt from the solutions of the present invention, and hence thechange in pH from this cause, is reversible. This means that if suchsolutions after being concentrated by evaporation (or heated) are againdiluted (or cooled, as the case maybe) the separated salt is redissolvedand the pH rises again; Accordingly the pH can be reduced as required byremoval of Solvent from th sol ions and an al o be in reased a ysubsequent ilu o he efie o h s is at when fibres, yarns or fabrics whichhave been impregnated with the solutions of the present invention arecured by baking at high temperatures,.the acidity is high under theconditions of curing but on standing the moisture which is alwaysabsorbed by such materials from the atmosphere dissolves up the salts,giving rise to solutions of markedly higher pH, g

A further advantage obtained with certain of the catalysts hereindescribed, notably with magnesium dihydrogen phosphate or magnesiumsulphate and sodium dihydrogen phosphate,'is that the pH value obtainedunder the conditions of normal stenter drying is not sufficiently low tobring about appreciable resin fixation, which fixation it is desirableto avoid at this stage if the resin is to be insolubilised in thepresence of a high proportion of superheated steam or if the impregnatedfabric is to be calendered or embossed before resin insolubilisation.

The invention will be further illustrated with reference to theaccompanying drawings. In all the figures the pH is plotted as ordinateand the logarithm (to base 10) of the molar concentration as abscissa.FIGS. 1 to 4 are graphs showing idealised curves for the change in pH atroom temp rature with the logarithm of the molar concentration C ofsolutions of methyl dihydrogen phosphates. FIG. 5 is a graph showingcurves obtained at room temperature by experiment for the change in pHwith the logarithm of the molar concentration C of aqueous solutions ofvarious metal dihydrogen phosphates. FIGS. 6 to 11 are a set of graphsshowing curves obtained at room temperature by experiment for the changein pH with the logarithm of the molar concentration C of aqueoussolutions of various metal acid salts.

Referring to FIG. 1 of the drawings, curve X represents in idealisedform the change in pH with the logarithm of the molar concentration of asolution of the dihydrogen phosphate of a metal whose dihydrogenphosphate will first separate out on increasing the concentration of thesolution by evaporation. The rate of change of pH (shown by the slope ofthe curve) remains substantially constant over the whole range ofconcentration until separation of the metal dihydrogen phosphate occursafter which no further change in concentration can take place (since thesolution is saturated with the dihydrogen phosphate) and accordingly thepH itself remains constant. Curve Y represents in idealised form thechange in pH with the logarithm of the molar concentration of a solutionof the dihydrogen phosphate of a metal whose monohydrogen phosphate ortrimetal phosphate will first separate out on increasing theconcentration of the solution by evaporation, i.e. a selected metal. Itis at once apparent that the rate of change of pH does not remainconstant over the whole range of concentrations but is at first acomparatively low value. This initial rate of change, because it isdetermined substantially entirely by the rate of increase of hydrogenion concentration due to removal of solvent, is practically the same asthe rate of change represented by curve X. However, curve Y difiers fromcurve X in that the rate of change of pH alters abruptly to a highervalue and finally returns to another low value. The concentration c atwhich this abrupt alteration in the rate of change .of pH occurs is thatwhich is termed herein the critical concentration and its value willdepend on the metal cation ofthe selected metal dihydrogen phosphateused. The critical concentration'will of course vary somewhat withtemperature, the extent and direction of such variation again dependingon the metal cation of the selected metal dihydrogen phosphate used.

This cri ical concentra ion is th PQiJ t a wh ch th selected metalmonohydrogen or trimetal phosph to begins to separate. When this happenshydrogen ions are liberated and the pH of the solutionthereafteradepends on two factorsfifirstly on the rate at which hydrogenions are liberated and secondly on the rate of increase 13 of hydrogenion concentration due to removal of solvent. For some time after theseparation of the selected metal monohydrogen or trimetal phosphatebegins, the major factor determining the rate of change of pH is therate of liberation of hydrogen ions. As the amount of selected metalions remaining in solution decreases however, a stage is reached whenthe liberation of hydrogen ions ceases to be the major factor indetermining the rate of change of pH and this rate is determinedprimarily by the rate of increase of hydrogen ion concentration byremoval of solvent. At this stage the rate of change of pH decreases asindicated by the change in slope of the curve at d. In practice, ofcourse, this change would not be abrupt as shown, but would be moregradual.

FIG. 2 is an idealised graph illustrating the dependency of the criticalconcentration on the nature of the selected metal. In this ideal form itis assumed that the pH of the solution at concentrations below thecritical concentration is independent of the nature of the selectedmetal, so that the initial pH indicated by a on the graph will be aconstant for a given initial concentration. With a given selected metalk having a low critical concentration (as increasing the concentrationof the solution by evaporation gives a curve which follows the path ac dIf a selected metal k whose critical concentration (at 0 is higher isused, the curve follows the path a-c d Since the critical concentrationis in fact the point at which the solution becomes saturated withrespect to either the monohydrogen or the tri-metal phosphate of theselected metal, the point at which the pH beginsto fall rapidly isdetermined by the solubility of either the monohydrogen or trimetalphosphate, of the selected metal. It is to be understood here that theterm solubility refers to the solubility under the particular conditionsprevailing in the solution and not to the absolute solubility in a puresolvent.

FIG. 3 illustrates the case where the salt which is first precipitatedcan exist in more than one form (eg. hy-

drates) having different solubilities. In the case considered it isassumed that two forms exist, one f stable below a temperature I and theother stable above this temperature. It is also assumed that the formstable above t has a lower solubility than the form stable below 2.Increasing the concentration of the solution by evaporation gives, belowt, a curve following the path ac d e and above t, following the path acd e In form therefore, the two curves are similar to the graph shown inFIG. 2 the two forms being equivalent to two dihydrogen phosphates ofdiflFerent selected metals. The system considered here, however, isdifferent from that of FIG. 2 in that it is possible to change over fromone curve to the other without change of selected metal. Thus, if asolution of f is made below t and of a concentration below the criticalconcentration of f e.g. at point a on the graph and the solution isevaporated at a temperature below t until the point x is reached, and ifthen the temperature is quickly raised above t, the criticalconcentration of will be exceeded and f will separate until the solidprecipitate is in equilibrium with the solution, i.e. at x on curve Onfurther evaporation of the solution keeping the temperature above t, thecurve will then follow the path x -d e The change in the pH, x to x whenf separates under such a temperature increase is almost instantaneousand, since it is a phase change, will be independent of otherconstituents in the solution. The amount by which the pH drops withoutfurther evaporation on exceeding the temperature 1 will depend on theamount by which the concentration of the solution exceeds the criticalconcentration of f Thus, if the evaporation of the solution is continuedto the point 3 on curve a-c d e before the temperature is caused toexceed 2, then the pH will fall to a point y between d and 2 on curvea-c d e Since the drop in pH on evaporation of the solution between :1and e is small relative to that which occurs between c and d or y and ythe effect of increasing the temperature beyond 2 is to produce almostthe maximum possible drop in pH practically instantaneously. If theevaporation of the solution below 'i is carried on until the point Z isreached on curve ac d -e the critical concentration of f will have beenexceeded and the rate of change of pH will have already increased. Rapidincrease of temperature beyond t will then cause the pH to droppractically instantaneously to a point represented by Z on curve a-c d ewhich thus has the efiect of producing practically instantaneously thepH drop which would normally occur between 2 and d on furtherevaporation of the solution at a temperature below t.

It will be apparent that if the separation of f upon removal of solventis delayed by supersaturation, the effect will simply be that line x xis moved to the right and the almost instantaneous drop in pH, when itoccurs, will be all the greater. If separation of the monohydrogenphosphate or trimetal phosphate of the selected metal illustrated inFIG. 2 upon removal of solvent is delayed by supersaturation, then thepH will undergo a sudden drop when separation does take place,undergoing a change similar to that shown by a-x -x -d on FIG. 3.

FIG. 4 illustrates the effect of different degrees of buffering on thechange in pH which occurs when the concentration of a. solutionaccording to the present invention is increased by evaporation.Referring to the drawing, curve a -c -d-e represents in idealised formthe change in pH obtained on evaporating a solution, not containing abuiier, of the dihydrogen phosphate of a selected metal of initialconcentration c This curve is similar to that illustrated by curve Y ofFIG. 1. If a bufifering agent is added in an amount sufficient to theinitial pH from the point al to that at a and the solution is thenevaporated the curve follows the path a -c de. Again, if the amount ofbuffering agent added is sufiicient to raise the initial pH to the pointrepresented by a on evaporating the solution the curve will follow thepath a c -de. The critical concentration (as hereinbefore defined) forthese three curves are represented by the points c c and c and it isseen from the graph that 0 c c This relation is a characteristicproperty of the solutions of the present invention, i.e. that theaddition of a buffering agent lowers the critical concentration. It isto be noted that these critical concentrations all lie on the extensionof line dc of curve a --c -de. This means that the rate of change of pHwith concentration, after the critical concentration has been reached,is unafiected by the bufiering. In fact, the rate of change of pH beforethe critical concentration is reached is also unaffected by thebuffering, as is shown by the parallel relation of lines a -c a e, and a-c but this is of no importance. From the above relation it is to beexpected that as the amount of buffering agent added is increased andthe critical concentration consequently decreased, a stage will bereached when the critical concentration becomes equal to the initialconcentration of the solution. Such a stage does, in fact, occur and isrepresented on the graph by the point a c.,, which point lies at theintersection of the extension of line c -a and the extension of line d-cSince at the critical concentration, the solution is saturated withrespect to the monohydrogen phosphate of the selected metal, any furtheraddition of buifering agent will cause precipitation of thissalt with aconsequent lowering in the concentration of the ions of the selectedmetal and therefore also of dihydrogen phosphate of the selected metalin the solution. The change in pH with addition of buffering agent willthen follow the curve a -h.

It is, of course, not desirable that the initial pH be raised beyond thepoint at which the critical concentration becomes equal to the initialconcentration of the solution since this would lead to a loss of ions ofthe selected metal from the solution. The point a c thus represents themaximum pH to which it is desirable to butter the solution. This maximumpH is however easily determinable by finding the point of intersectionof the extensions of lines c a and dc FIG. 5 is -a graph showing curvesobtained at room temperature by experiment for the change in pH with thelogarithm of the molar concentration C of aqueous solution of variousmetal dihydrogen phosphates. On the graph the curves are indicated bythe chemical symbol of the selected metal concerned; thus Mg is thecurve for magnesium dihydrogen phosphate [Mg(H PO Where a selected metalcan have more than one acid dihydrogen phosphate according to itsvalency state the particular valency state is indicated by positivecharges, thus Ferrous is written as Fe++. For comparison, the curves forsodium dihydrogen phosphate (indicated by the chemical symbol Na) andfor orthophosphate (indicated by the chemical formula H PO are alsoshown.

FIGS. 6-11 are graphs similar to that of FIG. 5 showing curves obtainedat room temperature by experiment for a change in pH with the logarithmof the molar concentration G of aqueous solutions of various other metalacid salts. Theparticular systems illustrated are as follows:

FIG. 6. Hydrogen malonate systems.

RIG. 7. Hydrogen succinate systems.

FIG, 8. Dihydrogen citrate systems.

FIG. 9. Hydrogen maleate systems.

FIG. 10. Hydrogen malate systems.

FIG. 11. Hydrogen tartrate systems.

In each case the curves are indicated by the chemical symbol of theselected metal concerned. For comparison curves for the sodium acidsalt-and for the free acid are also shown in all the figures. The curvesfor the sodium salts are indicated in each case by the chemical symbolNa and the curves for the free acid are indicated by the empiricalformula for the particular acid concerned; i.e.

FIG. 6. C 'H O malonic acid. FIG. 7. C H O succinic acid. FIG. 8. C H OH 0, citric acid. FIG. 9. C H O4, maleic acid.

FIG. 10. C H O malic acid. FIG. 11. c 5 0, tartaric acid.

It is known from our British patent specification No.

467,489 that fabrics and other textile materials can be delustred and/orweighted by precipitation thereon of an insoluble non-resinouscondensation product in the form of finely divided particels from ureaor urea-like substances and formaldehyde or from soluble partialcondensates thereof used for impregnating the material, by the additionof an acid or a substance liberating an acid before, during or afterimpregnation so that the precipitate is formed directly on the textilematerial. The precipitant used in that process is preferably an acidand' the textile material may be impregnated with any two of the threecomponents of the reaction and then treated with the third, or may beimpregnated with any one of the three components and then treated withthe other two. Insoluble condensation products of urea and formaldejhydein the form of white, amorphous discrete particles (known as methyleneureas) are excellent delustrants and are capable of being formed byprecipitation at ordinary temperature. If heat is used at all in thepreparation, it is necessary carefully to avoid either an unduly hightemperature or an excessive time of heatingQotherwise synthetic resinformation will take place. Although the precipitant is an acid, theurea-formaldehyde mixture may contain a potential precipitant (i.e. onecapable of liberating the acid precipitant under the conditions oftreatment) e.g. the ammonium salt of an acid, which acid will then beliberated on warming or treating the impreg- 16 nated material with wetsteam, provided that resin-formation is avoided.

Delustring is quite easily accomplished with the aid of aqueoussolutions containing the ingredients of aminoaldehyde condensationproducts according to the present invention, by simply impregnating atextile fabric with a solution whose composition is so chosen that theprecipitation of condensation product takes place on mere heating or onevaporation before more than a minor proportion of the water has beenremoved, and then drying the fabric and/or heating it to bring aboutsuch precipitation. After such precipitation the dried fabric may befurther heated, for example to a temperature above C. to form insolubleresinous condensation products from any remainingresin-formingingredients'.

One advantage of using the solutions of the present in vention fordelustn'ng textile materials is that the' delus tring eifect and thequantity of particulate precipitate which is formed can be more easilycontrolledthan' is the known process. Another advantage is that it ismore easy, with the solutions of the present invention, to combine thedelustring with improvement in the properties of the textile materials,such as improved resistance to creasing, consequent upon the formationof resinous condensations product within the fibres.

It has been found that when textile materials are delustred with thesolutions of the present invention, some of the salt of the selectedmetal which was precipitated on removal of solvent from and/or heatingof the solution is associated withthe condensation product whoseparticles are deposited on the textile material. If the textile materialis treated with a sequestering agent, as may happen in laundering, theselected me'talcan be removed and this removal may be accompani'ed byremoval of some or all of the particulate condensation product. r

This disadvantage can be reduced by using a selected metal which is notremoved by sequestering agents likely to be applied to the textilematerial. Thus, calcium salts are less suitable than barium, sincecalcium is more effectively sequestered than barium by sodiumhexametaphosphate, a compound which is contained in certain chemicaldetergent preparations. The disadvantage can also be minimised or evenavoided by ensuring that the solution contained in the fabric, afterdeposition of the condensation product in particulate form, stillcontains resinforming ingredients and by heating the textile materialafter drying to a sufficiently high temperature to form resinouscondensation products "from such ingredients. By doing this, there mayalso be conferred upon the fabric the known improvements in propertiesconsequent upon formation of synthetic resin therein, such as improvedresistance -to creasing. It is possible to produce'delustred patterns ona his trous background or lustrous patterns on a delustr ed backgroundby the use of solutions of the present invention. This can be done byprinting a fabric with a printing paste containing alkali, for examplecaustic soda, sodium carbonate or potassium carbonate and the usualother components necessary for successful printing, together with adyestuff if desired, drying, steaming if any dyestutt is used whichrequires this, and drying again if necessary, before impregnatingwiththe appropriate solution of the invention. The printed areas resistdelustring. Where the solutions of the presetn invention containing theingredients of amino-aldehyde condensation products are employed for thetreatment of textile materials to deposit resinous condensation productin the fibres thereof, for the production of effects such as resistanceto creasing, it is necessary to use solutions from which the less acidsalt of the selected metal will not be deposited until a majorproportion of the ionising solvent has been removed. Such solutions areused in the same way as the customary acid-catalysed solutions of theingredients of an amino-formaldehyde resin. The textilematerial isimpregnated with the solution, dried at a temperature below 100 C. andthe dried fabric heated for a short time, say 2 to 6 minutes at atemperature above 100 C., say 120 C.l80 C. A solution of a crystalloidalcondensation product such as is normally used for this type of processmay first be prepared and there may then be dissolved in it thenecessary salts, such as sodium dihydrogen phosphate and either calciumchloride or magnesium chloride, to make a solution according to thepresent invention.

The invention will be further illustrated by reference to the followingexamples, in which Examples 1 to 11 illustrate the use of the solutionsof the invention for improving the crease-resistance of textile fabrics,Examples 12 to 16 illustrate the preparation and use of solutions whosecritical concentrations have been increased by the addition of freeacid, Examples 17 to 19 illustrate their use for the delustring oftextile fabrics and Examples 20 to 25 illustrate their use for otherpurposes.

GR. is the assessment of crease-resistance obtained by measuringrecovery from creasing of a fabric which has been conditioned for a of24 hours in an atmosphere at 65% relative humidity and at 70 F., on theinstrument referred to on page 388 of Introduction to Textile Finishing,by I. T. Marsh, published by Chapman and Hall in 1948.

Ringwear is the assessment of abrasion resistance obtained by using theRingwear machine described in the Proceedings of the Textile Institute,1935, volume 26, p. 101.

Tensile Wp. is the assessment of the tensile strength in the warpdirection obtained by using a constant rate of traverse fabric tensiletesting machine as manufactured by Messrs. Goodbrand & Co. ofStalybridge, Cheshire, England, using fabric strips 1" wide in the weftdirection; the application of tension being applied in the wanpdirection, and the fabric strips having been conditioned for at least 24hours in an atmosphere of 65% relative humidity at 70 F.

Rip is the assessment of ripping strength obtained on a single threadtensile testing machine of suitable range manufactured by Messrs.Goodbrand & Co. of Stalybridge, Cheshire, England, and modified bypermanently raising the pawl on the quadrant arm, and providing a buiferto take the impact of the weight attached to the quadrant arm. The teststrips used are 12" long by 2" wide and are slit for 4" along the centreline of the fabric, one end of each half Width section being attached toeach jaw of the machine, and before testing each test strip isconditioned for at least 24 hours in an atmosphere of 65% relativehumidity at 70 F.

EXAMPLE 1 Production of crease resistance on cotton.

with known catalyst Comparison A urea-formaldehyde precondensate wasprepared as follows:

2375 cc. neutral aqueous 40% formaldehyde solution, 1000 g. urea, and100 cc. ammonium hydroxide (S.G. 0.88)

were mixed together and allowed to stand overnight.

Three impregnating solutions were prepared by mixing together:

(B) 310 cc. of the above precondensate solution,

70 cc. of a molar aqueous solution of magnesium chloride (approximately20.5% w./v. solution of MgCl .6H O

140 cc. of a molar aqueous solution of sodium dihydrogen phosphate(approximately 15.6% w./v. solution of NaH PO .2H O),

An aqueous solution of 10 g. of a softener such asdiethyl-amino-ethyl-alkyl-amino acetate, and water to make up 1000 cc.

(C) 310 cc. of the above precondensate solution,

120 cc. of a 10% solution of ammonium dihydrogen phosphate, NH H PO Anaqueous solution of 10 g. of a softener such asdiethyl-amino-ethyl-alkyl-amino acetate and water to make up 1000 cc.

The impregnating bath C was prepared for comparison purposes.

An s cotton square cloth was immersed in impregnating bath A, passedthrough a mangle adjusted to leave 68% (calculated on the dry weight offabric) of the solution on the fabric, and dried at 60 C. The driedfabric was heated for 3 minutes at 145 C., boiled for 20 minutes in anaqueous solution of 0.25% soap and 0.25 soda ash, rinsed in water,squeezed and dried.

Further pieces of a similar 80s cotton square cloth were immersed inimpregnating baths B and C and treated in a manner exactly similar tothe above. The figures for cloth tests canied out on the three sets ofsamples treated in impregnating baths A, B and C are set out in thefollowing table:

Resin, 0. R. Tensile Rip. Sample percent (warp Ringwear w.p. X warp weftand weft) A.. 8. 2 6. 7 1,440 34 890 860 B 9. 1 6. 7 920 34 820 720 C 8.4 6. 4 1,160 36 880 740 The stabilities of the three impregnating bathswere assessed by measuring the time taken for opalescence due to theprecipitation of methylene ureas to appear. The stability times were asfollows:

Precipitation time (hours) 24 24 5 EXAMPLE 2 Production ofcrease-resistance on rayon. Comparison with known catalyst Aurea-formaldehyde precondensate was prepared as follows:

1000 cc. neutral aqueous 40% formaldehyde, 500 g. urea, and 45 cc.ammonium hydroxide (S.G. 0.88)

were mixed together and allowed to stand overnight.

Three impregnating solutions were prepared by mixing together- .(B) 375cc. of the above precondensate solution,

cc. of a normal aqueous solution of magnesium dihydrogen phosphate(approximately 12.7% w./v. solution of Mg(H PO .2H 0),

Water to make up 1000 cc.

The impregnating bath C was prepared for comparison purposes.

A spun viscose rayon fabric was immersed in impregnating bath A, passedthrough a mangle adjusted to leave 80% (calculated on the dry weight offabric) of the solution on the fabric, and dried at 60 C. The driedfabric was heated for 3 minutes at 145 C., washed for 2' minutes in anaqueous solution of 0.25% soap and 0.25% soda ash, rinsed with water,squeezed and dried.

Further-pieces of a similar spun viscose rayon fabric were immersed inimpregnating baths B and C and treated in a manner exactly similar tothe above. The figures for cloth tests carried out on the three sets ofsamples treated in impregnating baths A, B and C above are set out inthe following table:

Resin, percent Sample X warp X weft qu er The resin washfastness ofthese samples was assessed by comparing the resin content of theunwashed fabrics with samples of these fabrics that had been washed for30 minutes at 90 C. in an aqueous solution of 0.25 soap and 0.25% sodaash. The Wash loss figures expressed as a percentage of the initialsolids content on the fabric were as follows:

Washloss, percent "I 31 The .bath stability times, assessed as describedin Example lwere as follows:

Precipitation time, hours 26 36 8 EXAMPLE 3 Production of creaseresistance. Use of ammonia-free impregnating solution 900 cc. of 'the.above. precondensate solution,

127.5 cc. of a molar aqueous solution of magnesium sulphate.(approximately 24.6% w./v. solution of 127.5 cc. of a molar aqueoussolution of sodium dihydrogen phosphate (approximately 15.6% .w./v;solution of NaH PO .2H O) Water to make up 1000 cc.

A spun viscose rayon fabric was immersed-in this impregnating bath,passed through amangle adjusted to leave-100% (calculated on--th e.dryweight of fabric) 'of' EXAMPLE 4 Production'of crease-resistance.Comparison of catalyst Systems with components thereof A series ofimpregnating solutions were prepared by mixing together:

(A) 30 cc. of a precondensate solution prepared as in Example 2, Asolution of 1.78 g. Mg(H PO ).2H O in about 30 cc. of water,

Water to make up 100 cc.

(B) 30cc. of a precondensate solution prepared as in Example 2,

10 cc. of a molar equeoussolution of magnesium sulphate (approximately24.6% w./v. solution of MgSO4.7I-I O),

10 cc. of a molar aqueous solution of sodium dihydrogen phosphate(approximately 15.6% w./v.

solution of NaH PO 2I-I O) Water to make up 100 cc.

(C) cc. of a precondensate solution prepared as in 30 Example 2,-

10 cc. of a molar aqueous solution of magnesium chloride (approximately20.5% w./v. solution of 10 cc. of a molar aqueous solution of sodiumdihydrogen phosphate (approximately 15.6% w./v.

solution of -NaH PO .2H O) Water to make up 100 cc. (D) 30 cc. of aprecondensate solution prepared as in Example 2, 40 10 cc. of a molaraqueous solution of magnesium sulphate (approximately 24.6% w./v.solution of MgSO .7I-I O),

Water to make up 100 cc.

(E) 30 cc. of a precondensate solution prepared as in Example 2,

10 cc. ofa molar aqueous solution of magnesium chloride (approximately20.5 w./v. solution of MgCl .6H O) Water to make up 100 cc.

(F) 30 cc. of a precondensate solution prepared as in Example 2,

10 cc. of a molar aqueous solution of sodium dihydrogen phosphate(approximately 15.6% w./v. solution of NaH PO 2H O),

55.' Water to make up cc.

. a fabric was subsequent-1y heated for 3 minutes at C.

Further lengths of a similar spun viscose rayon fabric were immersed inbaths B, C, D, E and F, and treated in a similar manner. The resinwashfastnessfigures, 70 measured as described in Example 2 were asfollows:

ABVODEF Wash loss, percent 25 27 28 81 72 45 EXAMPLE Production ofcrease-resistance. Use of impregnating solution having pH above 7 Animpregnating solution was prepared by mixing together:

180 cc. of a precondensate prepared as in Example 2,

72 cc. of a molar aqueous solution of lithium chloride (approximately 6%w./v. solution of LiClH O),

24 cc. of a molar aqueous solution of disodium monohydrogen phosphate(approximately 17.8% w./v. solution of Na HPO .2H O) Water to make up600 cc.

A spun viscose rayon fabric was then immersed in this impregnatingsolution and treated in the manner described in Example 3, except thatcuring was carried out for 3 minutes at 160 C. instead of 3 minutes at140 C. The resultant fabric possessed good crease resistance and goodresin washfastness.

The pH of the impregnating solution was 7.9 and it remained stable formany days.

EXAMPLE 6 Production of crease-resistance. Use of non-phosphate catalystsystem An impregnating solution was prepared by mixing together:

30 cc. of a precondensate prepared as in Example 2,

cc. of a molar aqueous solution of calcium chloride (approximately 21.9%w./v. solution of CaCl .6H O),

10 cc. of a molar aqueous solution of sodium dihydrogen malonate(approximately 14.4% w./v. solution of C H O Na.H O)

Water to make up 100 cc.

A spun rayon viscose fabric was then immersed in this impregnatingsolution and treated in the manner described in Example 3. The resultantfabric possessed good crease resistance and good resin washfastness.

EXAMPLE 7 Production of crease-resistance. Use of non-phosphate catalystsystem, and an ammonia-free impregnating solution Production ofcrease-resistance.

melamine Use of methylol 75 cos. of 40% w./v. commercial formaldehydesolution were taken and 5 cc. of 4% w./v. aqueous caustic soda was addedto make the pH of the resulting mixture 10.2.

42 gms. of melamine were added whilst mechanically stirring the mixtureand then 380 cc. of water at a temperature of 50 C. were added,mechanical stirring being continued at such a rate that solid melaminedid not settle, and until the melamine had dissolved. The resultingsolution which was slightly turbid was adjusted to pH 8.0 by theaddition of dilute hydrochloric acid, and then filtered through clothand the filtrate made up to a total 22 volume of 500 cc. to give asolution containing 14% w./v. of solids.

70 cos. of this solution were taken and 1% gms. of sodium dihydrogenphosphate (NaH PO 2H O) dissolved in 10 cc. of water and 2 /2 gms. ofEpsom salts (MgSO .7H O) dissolved in 10 cc. of water were added and thetotal volume made up to cc. with water. A spun viscose rayon fabric wasimmersed in this solution, nipped off through a mangle having a waterexpression of and dried at a temperature of about 60 C. When dry, theimpregnated fabric was heated in an oven for 3 minutes at C. to effectcuring. After heating, the fabric was Washed for 2 minutes in an aqueoussolution of w./v. soap and sodium carbonate at a temperature of 80 C.and then in hot and cold water, and then subsequently dried.

The resulting fabric possessed good crease-resistance and contained 8%resin.

EXAMPLE 9 Production of crease-resistance. Use of methylated methylolmelamine 7.5 gms. of a commercial melamine formaldehyde precondensateand containing about 80% w./v. of solids were dissolved in 50 ccs. ofwater. To this solution was added 1% gms. of sodium dihydrogen phosphate(NaH PO 2H O) dissolved in 10 cc. of water and 2 /2 gms. of Epsom salts(MgSO .7H O) dissolved in 10 ccs. of water and the resulting mixturemade to a total volume of 100 ccs. by addition of water.

A spun viscose rayon fabric was impregnated with the above solution,nipped off through a mangle having a water expression of 110% and driedup at a temperature of about 60 C. After drying the fabric was baked for3 minutes at C. and then Washed for 2 minutes in an aqueous solutioncontaining w./v. of soap and w./v. of sodium carbonate and then in hotand cold water. After drying the resulting fabric contained 4.5% resinand had good crease-resistance.

EXAMPLE 10 Production of crease-resistance by successive impregnationwith two solutions A spun viscose rayon fabric was immersed in adecimolar solution of sodium dihydrogen phosphate (approximately 1.55%w./v. solution of NaH PO .2H O), passed through a mangle adjusted toleave 100% (calculated on the dry weight of fabric) of the solution onthe fabric, and dried at 60 C.

An impregnating solution was prepared by mixing together:

500 cc. of a precondensate prepared as in Example 2,

100 cc. of a molar aqueous solution of magnesium sulphate (approximately24.6% w./v. solution of MgSO .7H O),

Water to make up 1000 cc.

The dried fabric was then immersed in this impregnating solution andtreated in the manner described in Example 5. The resulting fabricpossessed good creaseresistance and resin washfastness.

EXAMPLE 11 Production of crease-resistance: Comparison of impregnatings0luti n containing a buflering agent with an impregnating solution notcontaining a buffering agent Two urea-formaldehyde precondensates wereprepared as follows:

(A) 200 cc. of neutral aqueous 40% formaldehyde solution, 100 g. urea, l1.7 g. borax,

were mixed together and allowed to stand overnight.

(B) 200 cc. of-neutralaqueous formaldehyde solution,

100 g. urea,

were mixed together and allowed to stand overnight.

Two impregnating solutions were prepared as follows:

A sample of a spun rayon fabric was immersed in im pregnating solutionI, passed through a mangle having a water expression of 100% and driedat a temperature of 60 C. When dry, the impregnated fabric was heated 1nan oven for three minutes at l40"- C. to effect curing. After heating,the fabric was washed-in an aqueous solution of 0.25% soap and 0.25%soda ash, rinsed, squeezed and dried. Theresulting fabric possessed goodcreaseresistance and resin washfastness.

A further piece of a similar spun viscose rayon fabric was immersed inimpregnating solution II and treated in a manner exactly similar to theabove. Thislatter fabric also possessed good crease-resistance and resinwashfastness.

The stabilities of the two impregnating solutions assessed as in Example1 were respectively 40 hours to 1 /2 hours.

EXAMPLE 12 Use of free. acid to increase critical concentration 40.0 g.of pure magnesium oxide was added to about 750 cc. of distilled waterand the mixturewas stirred vigorously for about five minutes. Then 36.8cc. of glacial acetic acid was added to this solution, and with constantstirring 121 cc. of concentrated aqueous phosphoric acid (S.G. 1.75) wasallowed to drip in at-a rate sufficient for its own heat of reaction tokeep the temperature below 60 C. When all the phosphoric acid had-beenadded, in the solution was stirred until clear, and made up to one litrewith distilled water. On standa ing it did not deposit solid.

Theabove solution, which was stable over a long period, represents amolar solution of'magnesium'dihydrogen phosphate, in which thereis alsopresent acetic acid to an extent of 0.32 equivalent on the dihydrogenphosphate anion. A solution prepared in a similar way but in the absenceof acetic acid produced, on standing,

a solid precipitate of magnesium monohydrogen phosphate which would notdissolve without dilution.

EXAMPLE 13 Use of free acid to increase critical concentration period,represents a twice-molarsolution of magnesium,

dihydrogen phosphate'containing 15% excess of phosphoric acid. Asolution prepared in a similar way but in the absence of any excess ofphosphoric acid;pro-

' duced, on standing, a solid precipitate of magnesium 24'- monohydrogenphosphate which would not dissolve without dilution.

EXAMPLE 14- Production of crease-resistance with solution containingfree acid A urea-formaldehyde precondensate was prepared by mixingtogether:

1000 g. urea, 3750 cc. 40% aqueous formaldehyde, and 85 cc. aqueousammonia (s.g. 0.88).

This mixture was allowed to stand overnight at room temperature.

The following day, an impregnating bath was prepared by mixing together:

600 cc. ofthe above precondensate,

25 cc. of the twice-molarsolution of magnesium dihydrogen phosphatecontaining an excess of phosphoric acid, whose preparation is described.above in Example 13,

Water to one litre.

Aspun viscose rayon fabric was immersed in this impregnating solution,passed through a mangle adjusted so that a quantity of-thesolutionequivalent to on the dry weight of the fabric remained on the fabric.The fabric was then dried at 60 C. The dried fabric was heated for3minutes at 150 C. in an atmosphere of steam, washed in an aqueoussolution of 0.25% soap and 0.25% soda ash, squeezed and dried. Thetreated fabrics recovery from creasing and the resin washfastness weregood, and closely similar to those obtained on samples whose treatmentwas similar in all respects except for the substitution of the abovecatalyst 'by a magnesium dihydrogen phosphate solution containing thesame quantity of magnesium but no excess of phosphoric acid. In thislatter case, the impregnating bath had .a pH about 0.3 .pH higher thanthat in which the excess phosphoric acid was present.

EXAMPLE 15 Use of free-acid toincrease critical concentration 56.0 g. ofpure magnesium oxide was added to 643 cc. of distilled water in whichhad previously been dissolved 343 g. ofheptahydrated magnesium sulphate,at a temperature of 60 C. Stirring was continued at this temperaturefor15 minutes, ,the suspension was cooled tophoric acid on the phosphateanion, andincorporating an equal molar concentration of magnesiumsulphate. This solution thereforeis 2.8 molar with respect both tomagnesiumand to dihydrogen phosphate, leaving the excess acid out ofconsideration. A solution prepared in a similar way but in. the absenceof anyexcessof phosphoric acid produced on standing a solid precipitateof magnesium monohydrogen phosphate which: would not dissolve withoutdilution.

EXAMPLEv 16 Use of free acid to increase critical concentration- 7.4g.of calciumhydroxide was stirred into a disper- S1011 with 83 cc. water,with theaid of a few drops of a polyethylenecxide dispersing. agent and2 cc. of tennormaLhydrochloric acid (36.5% w./v.) .were added andallowed to react. This dispersion was then added slowly and withvigorous stirring, to a solution of 20.8 g. pure anhydrous malonic acidin 100 cc. water, at a temperature of 40 C. When all the calciumhydroxide had been added the solution was stirred until clear. Aftercooling to room temperature its volume was 200 cc. On standing it didnot deposit solid.

The above solution, which was stable over a long period, represents ahalf-molar solution of calcium hydrogen malonate containing a 20% excessof hydrochloric acid calculated on the malonate ion. A solution producedin a similar Way but in the absence of excess acid produced on standinga solid precipitate of calcium malonate which would not dissolve withoutdilution.

EXAMPLE 17 Production of delustre by concentration A urea formaldehydeprecondensate was prepared as follows:

100 gms. Urea, 200 cc. of 40% formaldehyde solution neutralised to Thesewere mixed together and allowed to stand overnight. The followingmorning the mixture was gently heated until solution of the methylolureas which had separated overnight was complete and an equal volume ofwater added to the solution.

60 ccs. of this solution were taken. 15.6 cos. of a 10% aqueous solutionof sodium dihydrogen phosphate (NaH PO 2H O) and 11.1 ccs. of a 10%aqueous solution of calcium chloride, and 13.3 ccs. of water were added.

A piece of 10 shaft end satin having a filament viscose rayon warp and aspun viscose rayon weft was padded through the above solution, nippedoff through a mangle having a water expression of 110% and dried for 75minutes at 34 C. in an atmosphere having a relative humidity of 67%.

After drying the fabric was baked for 3 minutes at 140 C. then washedfor 5 minutes at 80 C. in a solution of 0.25 of soap and 0.25% soda, andafter washing free of soap and soda was dried. The resulting fabricpossessed a fairly matt delustred appearance.

A similar piece of fabric impregnated through a solution of 60 ccs. ofprecondensate, 15.6 ccs. of solution of sodium dihydrogen phosphate (NaHPO .2H O) and 24.4 ccs. of water; dried, washed and treated as theabove, showed no degree of delustre.

EXAMPLE 18 Production of delustre by heating 60 ccs. of dilutedurea-formaldehyde precondensate solution, prepared as in Example 16 weremixed with 20 ccs. of a molar aqueous solution of magnesium sulphate and20 ccs. of a molar aqueous solution of sodium dihydrogen phosphate,

A piece of 10 shaft 5 end satin having a filament viscose rayon warp anda spun viscose rayon weft was padded through this solution and nippedoff through a mangle having a water expression of 110%. The nippedoflifabric was passed for 1 minute through an atmosphere of 100% steam atatmospheric pressure. The resulting fabric was dried and then baked for3 minutes at 140 C. After baking the fabric was washed for 5 minutes ina solution of 0.25% soap and 0.25% soda ash at 80 C. and, after washingfree from soap and soda, was dried.

The resulting fabric possessed a good matt delustred appearance.

A similar piece of fabric impregnated through a solution of 60 ccs. ofprecondensate, 20 ccs. of molar aqueous solution of sodium dihydrogenphosphate and 20 cos. of Water, when steamed and subsequently treated asabove, showed no degree of delustre.

26 EXAMPLE 19 Production of lustrous prints on delustred ground bysingle impregnation A piece of 10 shaft 5 end satin having a filamentviscose rayon warp and spun viscose rayon weft was printed with aprinting paste of the following composition:

20% British gum or dextrin and corresponds to the formula (C H O -xH O(p. 159, 316, Merck Index, sixth edition, Merck and Co., Inc., Rahway,N.J., 1952).

8% trisodium phosphate,

2.5% Formusol which consists of a mixture of formaldehyde-sodiumbisulphite, NaI-ISO CH O, and formaldehyde-sodium-sulphoxylate, NaHSO-CH O (p. 144, 172, Chemical Synonyms and Trade Names, William Gardner,Crosby Lockwood and Son, London, England, 1926),

5% urea,

3% glycerol,

5% colour (Caledon, Jade Green XNZOO),

Bulk to cc. with water.

After drying the fabric was passed through a two-bowl mangle, the lowerbowl being wrapped with a woolen fabric and the bottom half of the saidbowl being arranged to dip into a trough containing an aqueous solutionof 15% magnesium sulphate (MgSO .7H O), 9% sodium dihydrogen phosphate(NaI-I PO 2H O) and 23% solids content of a urea-formaldehydeprecondensate, prepared as described in Example 16, the mangle pressureand the amount of woolen fabric wrapping being adjusted so that themangle transferred to the fabric 86% of water calculated on the dryweight of the fabric when the trough contained water. After passingthrough the mangle the fabric was immediately steamed for 1 minute at atemperature of 100 C., dried and then heated for 3 minutes at 140 C. Thesample was then immersed in 0.2% sodium perborate solution at 20 C. for20 minutes, washed and immersed in A hydrochloric acid for 15 minutes toensure complete delustring of the printed areas. The fabric was washedmd boiled for 1% hours in an aqueous solution of 4% soap, 4% soda toremove loose colour and loose delustrant and subsequently washed in warmwater and dried. After drying the fabric was seen to have lustrouscoloured printed areas on a delustred ground, and possessed goodcrease-resistance on both the delustred and lustrous areas.

EXAMPLE 20' Production of fireproof board and heat insulating pads Aurea formaldehyde resin bonding syrup was made by dissolving grams ofurea in 280 grams of 40% w./v. commercial formaldehyde solution whichhad previously been brought to pH 7 with dilute caustic soda solution.After the urea had completely dissolved, 6 ccs. of 10% w./v. causticsoda solution was added with stirring and when the addition wascompleted, 5 ccs. of ammonia solution (specific gravity 0.880) wasadded, stirring being continued until the addition of the ammoniasolution was completed. The resulting solution was refluxed for 2 hoursand then allowed to cool. When cold, the pH was measured and found to be7.84. The pH of the solution was then adjusted to 7.4 by the addition ofdilute acetic acid (24% w./v.) and then concentrated under reducedpressure until 55 ccs. of water had been removed, care being taken toavoid raising the temperature of the solution above 45 C. during theconcentration.

The resulting syrup was filtered through a glass wool pad to removeslight traces of suspended solid.

To 45 cos. of the above bonding syrup was added 5 ccs. of an 11% w./v.aqueous solution of magnesium dihydrogen phosphate (Mg(H PO and theresulting mixture which was stirred to ensure uniformity of mix ing wasused to thoroughly impregnate a loosely packed pad of glass fibres.After impregnation, the pad of glass fibres was sandwiched between twolayers of cotton fabric and the sandwich placed in a centrifuge cage 9"diameter and rotated at a rate of 2200 revolutions per minute for 30seconds, after which time the fibres were only just moistened withsyrup. The sandwich was then removed, the cotton fabric layers strippedoif the glass fibre pad and the latter dried at 40 C. and then dividedinto two portions.

The first portion was placed in a heating press and compressed for 10minutes at 160 C. and at an applied pressure of 150 lbs. per squareinch. When the pressure was released the pad was found to be convertedinto a hard board extremely suitable for fireproof screening purposes.

The second portion was placed on a wire gauge table in a baking ovenfitted with a fan to give. eflicient circulation of the oven atmosphere,and baked for 6 minutes at 140 C. At the end of this period, the pad wasremoved and found to be a porous, resilient, non-sticky pad from whichfibres did not readily become detached, and was in an extremely suitableform for heat insulation purposes; even-when immersed in boiling waterfor 10 minutes it did not disintegrate.

EXAMPLE 21 Cotton filtration sheeting A magnesium dihydrogen phosphatecatalysed urea formaldehyde bonding syrup prepared as in Example 19 wasused to thoroughly impregnate a loosely packed pad of cotton wool. Afterimpregnation the pad of cotton wool was sandwiched between layers ofcotton fabric and centrifuged for 30 seconds in a centrifuge cage of 9"diameter rotating at 2200 revolutions per minute. After centrifuging thesandwich was removed and the protectingcotton fabric stripped off thecotton wool pad and the pad then dried at 40" C. and then baked for 6minutes between heated platens, the pressure applied being 12 lbs. persquare inch; At the end of this period the pad was removed and found tohave been converted'into a thin resilient porous sheet very suitable forfiltration purposes which did not disintegrate even after 10 minutesimmersion in boiling water.

EXAMPLE 22 Cross laminated paper A magnesium dihydrogen phosphatecatalysed urea formaldehyde bonding syrup as prepared in Example 19 wasused to impregnate sheets of crepe paper towelling. The excess surfaceliquor was removed by passing through a 13 domestic type mangle. Afternipping the sheets were dried at 40 C. and after drying,'11 sheets werestacked one on top of the other so that the direction of crepeing onadjacent sheets was at right angles. The resulting stack was cured in ahot press for 45 minutes at a temperature of 150 C. and at a press of150 lbs. per square inch.

.After removal from the press it was found that the paper had beenconverted into a thin board closely resembling wood veneer, whichremained substantially unchanged afterimmersion in boiling water for 30minutes;

EXAMPLE 23 Preparation of moulding powder Aquantity of paper as used inExample 21 was boiled for 1% hours in N/ 10 hydrochloric acid solution(0.365%

w./v.) to remove bonding material and the resulting the press the powderwas found to be converted into a hard translucent brown sheet which evenafter immersion for 2 minutes in hot water, followed by pad drying,possessed an electrical resistance of some hundreds of megohms at anelectrode separation of less than 1 millimetre.

EXAMPLE 24 Resin bonded plywood A phenol formaldehyde bonding syrup wasprepared by dissolviing 180 grams of phenol in 150 cos. of commercial40% w./v. formaldehyde. When solution of the phenol was complete, 40cos. of 40% w./v. caustic soda solution was added and the mixtureallowed to stand at room temperature for 16 hours. At the end of thisperiod the resulting syrup was neutralised to pH 7.0 with concentratedhydrochloric acid and then extracted with ether and the etherealsolution evaporated under reduced pressure until no further ether couldbe removed.

Two 10 cc. samples of the above phenol formaldehyde bonding syrup weretaken and to one sample was added 0.5 gram of crystalline magnesiumperchlorate and to the other sample was added 0.5 gram of crystallinesodium dihydrogen phosphate. The samples were then shaken and allowed tostand for half an hour. At the end of this period, the sodium dihydrogenphosphate containing sample was decanted to give a clear solutionhereinafter termed Solution A. The magnesium perchlorate containingsample was decanted to give a clear solution termed hereinafter SolutionB.

Equal volumes of Solutions A and B were mixed and allowed to stand andafter several hours showed no signs of depositing any solid precipitate.

Two wood veneers were taken, one painted on one side with Solution A andthe other painted on one side with Solution B. The two veneers were thenplaced one on top of the other with their treated sides in contact and.so placed that the wood grains of the two veneers were at right anglesto one another. The two pieces were then placed in a heated pressandcuredfor 10 minutes at 180 C. at an applied pressure of 500 lbs. persquare inch. At the end of this period the vcnecrs were found to befirmly bonded together, the bond being such that after boiling theveneers for 10 minutes in water, no deterioration of the bond wasapparent.

7 EXAMPLE 25 Bonded non-woven viscose rayon fibres A thin layer ofcarded viscose rayon staple fibre of weight 3.7 grams per square footwas sandwiched between two layers of cotton fabric and passed through amangle the bottom bowl of which was wrapped with a woollen material andwhich dipped in a trough of urea formaldehyde bonding syrup as preparedin Example 19.

The woollen wrapping was adjusted so that the weight of syruptransferred to the sandwiched layer of viscose staple was of the dryweight of the viscose. The cotton fabric was then stripped from theviscose and the latter dried at 60 C. When dry, the treated viscose wasdivided into two parts.

The first part was taken and cured between the paper covered platens ofa hot press for 15 minutes at C. and at'an applied pressure of 1000 lbs.per square inch. The resultant thin layer of viscose staple was a stickymass which readily disintegrated on handling.

The second part was taken and sprayed'with an 11% W./v. aqueous solutionof magnesium dihydrogen phosphate until the viscose layer containedabout 8% of its weight of magnesium dihydrogen phosphate solution.

The sprayed viscose layer was then dried at 60 C. and

1. AN AQUEOUS SOLUTION OF THE INGREDIENTS OF AN ALDEHYDE RESIN SELECTEDFROM THE GROUP CONSISTING OF UREAFORMALDEHYDE, MELAMINE-FORMALDEHYDE,AND PHENOLFORMALDEHYDE RESINS, WHOSE FORMATION IS CATALYZED BY ACID,CONTAINING IN SOLUTION AN ACID SALT OF A POLYBASIC ACID SELECTED FROMTHE GROUP CONSISTING OF PHOSPHORIC, PHOSPHOROUS, PYROPHOSPHORIC,MALONIC, MALIC, MALEIC, TARTARIC, AND SUCCINIC ACID HAVING A FIRSTDISSOCIATION CONSTANT IN WATER OF AT LEAST 10-6, AND ALSO A SALT WITH ANACID STRONGER THAN SAID POLYBASIC ACID OF A METAL SELECTED FROM THEGROUP CONSISTING OF LITHIUM, BARIUM, CALCIUM, STRONTIUM, MAGNESIUM,ZINC, COPPER, FERROUS IRON, MANGANESE, CADMIUM AND COBALT OF WHICH ALESS ACID SALT WITH SAID POLYBASIS ACID WILL SEPARATE FROM THE SOLUTIONBEFORE THE ACID SALT OF SAID METAL WITH SAID POLYBASIC ACID WHEN WATERIS REMOVED FROM SAID SOLUTION.